Due to the inaction of state and federal officials, thousands of people in Flint have been exposed to unsafe levels of lead in their water. Now a group of union plumber are taking matters into their own hands.

For some in Flint, however, even new faucets with modern water filters won’t be enough to fully abate the lead contamination. New tests released recently revealed that, in some Flint homes, the levels of lead “exceed the ability of filtration systems handed.” The filters can safely remove up to 150 parts per billion of lead. Some Flint homes were found to have lead levels of more than 4,000 parts per billion.

Residents of Flint, however, are still encouraged to use the filters. For most homes, they will work.